Caliptra Update-Reset Secure-Boot Bypass via Attacker-Chosen AXI Staging Address (TOCTOU)

{
  "id": "12ef563baa5820c0bb2243cc335993d69c52194142613da7d379ee88a2bcc168",
  "url": "https://osv.dev/vulnerability/CVE-2026-11835",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Caliptra Update-Reset Secure-Boot Bypass via Attacker-Chosen AXI Staging Address (TOCTOU)",
    "summary": "Time-of-check time-of-use (TOCTOU) vulnerability combined with missing input validation in Caliptra Core ROM (UpdateResetFlow::run()) in subsystem mode allows a compromised local attacker to silently bypass secure boot by supplying an AXI staging address that is not validated against the strap-configured SS_EXTERNAL_STAGING_AREA_BASE_ADDR, enabling firmware to be modified between verification and loading into ICCM. Attestation continues to report the originally verified image digest, masking the compromise. Exploitation requires a compromised MCU firmware with AXI manager access to unprotected SRAM reachable by Caliptra. This issue affects Core ROM: 2.1.0 through 2.1.1.",
    "evidence": "osv:CVE-2026-11835",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-11835",
      "aliases": [
        "CVE-2026-11835",
        "GHSA-49mm-5gq5-v97f"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:L/AC:H/AT:P/PR:H/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/chipsalliance/caliptra-sw",
              "type": "GIT",
              "events": [
                {
                  "introduced": "a72a76f234d9f7069ddd1e8b8ebef30a9c3fa326"
                },
                {
                  "last_affected": "510a23adbc911e8e72708799daba964ec045ef25"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "2.1.0"
                      },
                      {
                        "last_affected": "2.1.1"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "range": [
                      {
                        "introduced": "2.1.0"
                      },
                      {
                        "last_affected": "2.1.1"
                      }
                    ],
                    "source": "DESCRIPTION"
                  }
                ]
              }
            }
          ],
          "versions": [
            "rom-2.1.1",
            "release_v20260331_0-2.x",
            "release_v20260319_0-2.x",
            "release_v20260317_0-2.x",
            "release_v20260312_0-2.x",
            "release_v20260310_1-2.x",
            "fw-2.1.0",
            "release_v20260310_0-2.x",
            "release_v20260218_0-2.x",
            "release_v20260217_0-2.x",
            "release_v20260214_0-2.x",
            "rom-2.1.0",
            "release_v20260207_1-2.x",
            "release_v20260207_0-2.x"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-11835.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:51.260841150Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/11xxx/CVE-2026-11835.json",
        "https://github.com/chipsalliance/caliptra-sw/security/advisories/GHSA-49mm-5gq5-v97f",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-11835",
        "https://github.com/chipsalliance/caliptra-sw"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-20",
          "CWE-367"
        ],
        "cna_assigner": "Caliptra",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/11xxx/CVE-2026-11835.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-11835",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 519988,
  "published_at": "2026-08-04T00:03:23.278+00:00"
}